CN101774028A

CN101774028A - Method for preparing Ni-BaTiO3 compound powder

Info

Publication number: CN101774028A
Application number: CN200910044783A
Authority: CN
Inventors: 李启厚; 刘志宏; 刘智勇; 吴希桃; 李玉虎
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2009-11-20
Filing date: 2009-11-20
Publication date: 2010-07-14
Anticipated expiration: 2029-11-20
Also published as: CN101774028B

Abstract

The invention discloses a method for preparing Ni-BaTiO3 compound powder, which has the steps as follows: adding tetraisopropyl titanate source in a nitric acid solution to prepare a Ti source solution; adding soluble salts of Ni and Ba and reducing agent urea to prepare a precursor solution in terms of stoichiometric ratio; and spraying the solution in a vertical type reaction furnace in an ultrasonic spraying mode, and performing thermal decomposition reaction at the temperature of 750-1,000 DEG C to prepare the Ni-BaTiO3 compound powder.

Description

A kind of Ni-BaTiO 3The preparation method of composite powder

Technical field

The present invention relates to the preparation method of a kind of metal and dielectric ceramic composite powder.

Background technology

Metal Ni except that having the characteristics that cost is low and fusing point is higher, also possess electrical conductivity height, electromobility little, to advantages such as the corrosion resistance of scolder and good heat resistances, so the superfine metal nickel powder is widely used as chip multilayer ceramic capacitor (MLCC) inner electrode.But during producing, base metal chip multilayer ceramic capacitor (BME-MLCC) exists two large problems: first, because inner electrode Ni powder just begins to shrink at about 300 ℃, and sintering shrinkage reaches more than 20%, and ceramic dielectric layer just begins to shrink at 1100～1200 ℃, and sintering shrinkage is generally between 15%～20%.In sintering process, both difference in shrinkage will cause ftractureing between electrode and porcelain body like this, and this difference in shrinkage is big more, and the possibility of cracking and the order of severity are just big more.Therefore, electrode should have less sintering shrinkage with nickel powder in the MLCC, and is complementary with the shrinkage factor of dielectric material as far as possible.The second, oxidized its electric conductivity that reduces in order to adapt to the requirement of electrode MLCC oxidizing atmosphere sintering in the base metal Ni, has proposed the requirement of non-oxidizability to the Ni inner electrode thereby nickel inner electrode slurry and organic bond burn in air atmosphere altogether.

In order to address the above problem, people have carried out various trials, by the Ni powder being carried out technology such as surperficial organic decoration or inorganic coating, make composite, have improved the non-oxidizability of Ni powder and have improved sintering matching between the dielectric layer.

" Synthesis and characterization of BaTiO for example ₃-coated Ni particles " (Hatano T, Yamaguchi T, Sakamoto W, et al.Journal of the European Ceramic Society, 2004, (24): 507-510.) introduced a kind of preparation Ni-BaTiO ₃The method of composite has strengthened the non-oxidizability of Ni powder and the sintering matching between the dielectric layer to a certain extent.Be to use the Prepared by Sol Gel Method presoma earlier, use electric furnace high temperature (more than 600 ℃) calcining to obtain product then.Its weak point is, presoma needs through washing, the subsequent treatment that oven dry etc. are complicated, and necessary strict controlled atmospher in calcination process, otherwise be easy to oxidation with Ni, after high-temperature calcination, need to take out composite powder with the burner hearth cool to room temperature, otherwise Ni also can oxidation, needs more than 10 hour from the high temperature cool to room temperature more than 600 ℃, and must feed inert gas in the process of this cooling always.This has just caused, and production efficiency is low, cost is high.

Another the name be called " Nickel powder and process for preparing the same " (Asada E, Akimoto Y, Nagashima K, et al.US Patent 6007743, patent 1999-12-28) is utilized Ni (NO ₃) ₂6H ₂O, Ba (NO ₃) ₂, and TiO (NO ₃) ₂Mixed solution as precursor solution, adopt the spraying pyrolysis technique, at (CO or H about 1500 ℃, under the weak reducing atmosphere ₂Deng reducibility gas) made Ni-BaTiO ₃Composite granule.This invention the hot conditions of using very high to the requirement of equipment, cost is also high.

Summary of the invention

Purpose of the present invention is at the deficiencies in the prior art, and a kind of preparation Ni-BaTiO is provided ₃The method of composite powder.

The solution of the present invention is: under stirring condition, add the tetraisopropyl titanate of 0.006～0.063mol/L in concentration is the salpeter solution of 1～2mol/L, make Ti source solution; The Ba that adds 0.006～0.063mol/L then by recombination rate ²⁺, the Ni of 0.2～1.0mol/L ²⁺, the urea of 1.2～6mol/L is (by stoichiometric proportion Ba: Ti=1; CO (NH ₂) ₂: Ni=6), make precursor solution; Precursor solution is sprayed in the vertical reacting furnace with spray pattern, be 750～1000 ℃ in temperature and carry out pyrolysis, obtain Ni-BaTiO ₃Composite powder.Described Ba ²⁺Be barium acetate, Ni ²⁺Be nickel nitrate.

Consider that from improving productive rate preferable range is respectively: tetraisopropyl titanate is 0.025～0.063mol/L, Ni ²⁺Be 0.4～1.0mol/L, Ba ²⁺Be 0.025～0.063mol/L, urea is 2.4～6mol/L.

The inventive method has following advantage:

1. not only technological process is brief, operation compactness, continuous, and also desired treatment temp significantly reduces; The composite powder that makes does not need complicated subsequent treatment, directly adopts conventional means to carry out washing and drying and can obtain product;

2. it is easy to use to make reducing agent with urea, and only need allocate solution into and get final product, owing to need not use fuel gas, thus saved corresponding gas transmission system, simplified the reacting furnace structure, its security is simultaneously also worried about nothing;

3. recombination rate is easy to regulation and control, can accurately be prepared into the product of different composite rate on demand.

Description of drawings

Fig. 1 is the process chart of the inventive method;

The recombination rate that Fig. 2 prepares for the present invention is 10% o'clock Ni-BaTiO ₃The XRD figure of composite powder;

The recombination rate that Fig. 3 prepares for the present invention is 10% o'clock Ni-BaTiO ₃The XPS figure of composite powder.

The specific embodiment

Preparation method of the present invention is mainly following three steps:

The first step: the Ti source solution of configuration clear.Measure a certain amount of salpeter solution and put into beaker, under mechanical agitation, tetraisopropyl titanate (TTIP) is slowly added wherein.Nitric acid can suppress the hydrolysis of TTIP effectively, therefore can make the solution of clear.

In this step, red fuming nitric acid (RFNA) concentration is 1～2mol/L, and the TTIP consumption is 0.006～0.063mol/L, and temperature is a room temperature, and mixing speed is 300 rev/mins, and mixing time is 40～60min.

Second step: configuration compound precursor solution.After the first step finishes,, add barium acetate, nickel nitrate and urea by stoichiometric proportion according to required recombination rate requirement.Before stabilized complex can being clarified behind the stirring 30min, drive liquid solution.

In this step, addition is respectively: Ni ²⁺0.2～1.0mol/L, Ba ²⁺0.006～0.063mol/L, urea 1.2～6mol/L.Recombination rate generally gets final product in 10%～20% scope.

The 3rd step: spraying thermal decomposition.The precursor solution that second step was made passes through ultrasonic spray apparatus, uses N ₂For carrier gas fog is sent in the burner hearth of reacting furnace, made precursor solution generation thermal decomposition, obtain Ni-BaTiO ₃Composite powder.

In this step, reacting furnace is vertical resistance furnace, and its internal diameter is φ 100mm.The power of ultrasonic atomizer is 2.0MHz; A speed control of solution is built in 1～3mL/min; Temperature is 750～1000 ℃; Flow rate of carrier gas is 1～3L/min.

The 4th step: powder is collected.Collect the powder that is brought out by carrier gas with the beaker that 0.015～0.006mol/LNaOH solution is housed, and the product of collecting is spent deionised water 3 times, with absolute alcohol washing 3 times.In 70 ℃ of vacuum drying chambers, dry by the fire 2h again, promptly obtain final composite granule product.

Adopt the weakly alkaline NaOH aqueous solution to collect powder, can avoid in thermal decomposition process urea to decompose and nickel nitrate decomposes the harm to the environment generation of the toxic gas that produced.

For example the inventive method is illustrated again below:

Embodiment 1: the salpeter solution 25mL of measuring lmol/L puts into beaker, and the TTIP of measuring 0.42mL (0.006mol/L) more slowly adds wherein, behind the stirring 60min, obtains the settled solution of TTIP.Take by weighing the Ba (CH of 0.36g then ₃COO) ₂, 14.54g nickel nitrate and 18.02g urea (Ba ²⁺Be 0.006mol/L, Ni ²⁺Be 0.2mol/L, urea is 1.2mol/L, and recombination rate is 10%), add in the solution of titanium source, stir 30min, be made into the 250mL precursor solution.This precursor solution is fed in the reacting furnace by ultrasonic spray apparatus, and regulating temperature is 750 ℃, N ₂Gas velocity is 1L/min, and drop drips speed and is 1mL/min.The powder that makes is collected with the alkaline solution that NaOH is housed.

The XRD analysis result of Fig. 2 shows: powder is Ni and cubic BaTiO mutually ₃, do not contain NiO or BaCO ₃Deng dephasign.The xps energy spectrum of Fig. 3 the analysis showed that: Ba, Ti, four kinds of elements of O, Ni exist simultaneously on the individual particle, and Ba, Ti, three kinds of elements of O account for 9.53% of gross weight, and Ni accounts for 90.47% of gross weight, and this proportioning basically identical during with batching illustrates BaTiO ₃Be evenly distributed in the Ni powder.

Embodiment 2: the salpeter solution 25mL of measuring 1.2mol/L puts into beaker, and the TTIP of measuring 0.75mL (0.025mol/L) more slowly adds wherein, behind the stirring 60min, obtains the settled solution of TTIP.Take by weighing the Ba (CH of 0.64g then ₃COO) ₂, 11.63g nickel nitrate and 14.41g urea (Ba ²⁺Be 0.025mol/L, Ni ²⁺Be 0.4mol/L, urea is 2.4mol/L, and recombination rate is 20%), add in the solution of titanium source, stir 30min, be made into the 100mL precursor solution.This precursor solution is fed in the reacting furnace by ultrasonic spray apparatus, and regulating temperature is 1000 ℃, N ₂Gas velocity is 1L/min, and drop drips speed and is 1mL/min.The powder that makes is collected with the alkaline solution that NaOH is housed.

Testing result shows: powder is Ni and cubic BaTiO mutually ₃, do not contain NiO or BaCO ₃Deng dephasign.

Embodiment 3: the salpeter solution 25mL of measuring 2mol/L puts into beaker, and the TTIP of measuring 1.9mL (0.063mol/L) more slowly adds wherein, behind the stirring 60min, obtains the settled solution of TTIP.Take by weighing the Ba (CH of 1.6g then ₃COO) ₂, 29.1g nickel nitrate and 36.05g urea (Ba ²⁺Be 0.063mol/L, Ni ²⁺Be 1.0mol/L, urea is 6.0mol/L, and recombination rate is 20%), add in the solution of titanium source, stir 30min, be made into the 100mL precursor solution.This precursor solution is fed in the reacting furnace by ultrasonic spray apparatus, and regulating temperature is 1000 ℃, N ₂Air velocity is 3L/min, and drop drips speed and is 3mL/min.The powder that makes is collected with the alkaline solution that NaOH is housed.

Claims

1. Ni-BaTiO ₃The preparation method of composite powder is characterized in that, under stirring condition, adds the tetraisopropyl titanate of 0.006～0.063mol/L in concentration is the salpeter solution of 1～2mol/L, makes Ti source solution; The Ba that adds 0.006～0.063mol/L then by recombination rate ²⁺, 0.2～1.0mol/L Ni ²⁺, 1.2～6mol/L urea, be Ba: Ti=1, CO (NH wherein by stoichiometric proportion ₂) ₂: Ni=6 obtains precursor solution; Precursor solution is sprayed in the vertical reacting furnace, with N with spray pattern ₂Be carrier gas, be 750～1000 ℃ in temperature and carry out pyrolysis, obtain Ni-BaTiO ₃Composite powder; Described Ba ²⁺Be barium acetate, Ni ²⁺Be nickel nitrate.

2. preparation method according to claim 1 is characterized in that described tetraisopropyl titanate consumption is 0.025～0.063mol/L, described Ba ²⁺Consumption is 0.025～0.063mol/L, described Ni ²⁺Consumption is 0.4～1.0mol/L, and described amount of urea is 2.4～6mol/L.

3. preparation method according to claim 1 and 2 is characterized in that described recombination rate is 10%～20%.